Texas Instruments ISO35T Small EVM ISO35TEVM-434 ISO35TEVM-434 Scheda Tecnica
Codici prodotto
ISO35TEVM-434
V
IN
GND1
R
RE
DE
D
J1
C2
1
2
4
3
5
6
7
8
D1
D2
V
CC1
GND1
R
RE
DE
D
V
CC2
A
B
GND2
Z
Y
C3
16
14
13
12
11
15
9, 10
U1
V
OUT
GND2
A
B
Z
Y
OUT
NC
C6
IN
EN
GND
5
1
U2
1
3
2
C5
C4
D1
D2
8
7
6
6
5
4
3
2
1
C1
T1 !
!
!
!
!
!
Indicates components that
may be hot to touch
may be hot to touch
Reference Guide
SLUU470B
–
December 2010
–
Revised June 2011
Isolated, Full-Duplex, 1-Mbps, 3.3-V to 3.3-V RS-485
Interface
1
Circuit Function and Benefits
This circuit provides an isolated, 1-Mbps, 3.3-V to 3.3-V RS-485 interface using the ISO35T, isolated
RS-485 transceiver and the TPS76333 high-accuracy linear regulator. This circuit achieves signal and
power isolation and at the same time decreases board space and power consumption.
RS-485 transceiver and the TPS76333 high-accuracy linear regulator. This circuit achieves signal and
power isolation and at the same time decreases board space and power consumption.
Figure 1. Isolated, Full-Duplex, 1-Mbps, 3.3-V to 3.3-V RS-485 Interface
2
Circuit Description
The ISO35T is an isolated differential line transceiver with integrated transformer driver that provides the
primary voltage for an isolation transformer. The device is ideal for long transmission lines because the
ground loop is broken to allow the device to operate with a much larger common-mode voltage range. The
symmetrical isolation barrier of each device is tested to provide 2500 Vrms of isolation between the line
transceiver and the logic-level interface.
primary voltage for an isolation transformer. The device is ideal for long transmission lines because the
ground loop is broken to allow the device to operate with a much larger common-mode voltage range. The
symmetrical isolation barrier of each device is tested to provide 2500 Vrms of isolation between the line
transceiver and the logic-level interface.
The galvanically isolated differential bus transceiver is designed for full-duplex data communication on
multipoint bus-transmission lines. The transceiver combines a galvanically isolated differential line driver
and differential-input line receiver.
multipoint bus-transmission lines. The transceiver combines a galvanically isolated differential line driver
and differential-input line receiver.
Any cabled I/O can be subjected to electrical noise transients from various sources. These noise
transients can cause damage to the transceiver and/or nearby sensitive circuitry if they are of sufficient
magnitude and duration. The ISO35T can significantly reduce the risk of data corruption and damage to
expensive control circuits.
transients can cause damage to the transceiver and/or nearby sensitive circuitry if they are of sufficient
magnitude and duration. The ISO35T can significantly reduce the risk of data corruption and damage to
expensive control circuits.
The integrated transformer driver consists of an oscillator followed by a flip-flop stage generating two
complementary, 50% duty-cycle square waves. These two signals drive the ground-referenced N-channel
power switches. Internal circuitry ensures break-before-make action between the two switches.
complementary, 50% duty-cycle square waves. These two signals drive the ground-referenced N-channel
power switches. Internal circuitry ensures break-before-make action between the two switches.
1
SLUU470B
–
December 2010
–
Revised June 2011
Isolated, Full-Duplex, 1-Mbps, 3.3-V to 3.3-V RS-485 Interface
Copyright
©
2010
–
2011, Texas Instruments Incorporated